US2640465A

US2640465A - Power unit

Info

Publication number: US2640465A
Application number: US200954A
Authority: US
Inventors: Stewart B Mcleod
Original assignee: Detroit Harvester Co
Current assignee: Detroit Harvester Co
Priority date: 1950-12-15
Filing date: 1950-12-15
Publication date: 1953-06-02
Anticipated expiration: 1970-06-02

Description

June 2, 1953 A s. B. MOLEOD 2,640,465

' POWER UNIT Filed Dec. 15, 1950 2 Sheets-Sheet 1 FIG.I;

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L A I04 74 loo mmvrok STEWART B.McLE 0D POWER UNIT Filed Dec. 15, 1950 2 Sheets-Sheet 2 8 N 8 2 8'3 g 83$ .3 u. F2

. a L -1 o r N N o N w COO) l :3 l g w 1| N LO June 2, '1953 s. B. MOLEOD 2,640,465

INVEN TOR.

STE ART B. MCLEOD ATTORNE S Patented June 2, 1953 UNITED STATES PATNT OFFICE lPOWER UNT'I Stewart B. McLeod, Dearborn, Mich, assignor to Detroit liiarvester Qompany, Detroit, Mich, a corporation of Michigan Application December 15, 1950, SerialiNo. 2110;954

6 Claims.

The present invention relates to a power unit and more particularly to a combination electric driven pump and piston and cylinder device for effecting relative movement between parts in an automobile. The present construction is designed particularly io'r use in effecting automatic movement of the front seat of the vehicle to adjusted position and includes means for efiectively locking the seat in adjusted position when the 2 the seat 1 2 and connected at its otherend to a bracket I! carried by the seat. Thus, as the power unit is energized the seat is moved forwardly or rearwardly of the vehicle.

Referring now to Figures 2 7, the power unit comprises essentially a unitary base 20 preferably formed as a casting, having a cylindrical motor seat 22 formed thereon, a cylindrical pump recess 24 formed therein, a circular cylinder seat motor is de-energized. 26 formed thereon, and a bracket 28 extending It is an object of the present invention to therefrom. provide a power unit characterized by its com A rotary pump comprising an internally pactness, simplicity, and economy of constructoothed gear -30) and an externally toothed gear tioii. 32 is located in the pump recess 24, the recess It is a further object of the present inven being closed by a closure plate 34 suitably held tion to provide a power unit combining the adin place by screws 36 or the like. The motor vantageous features of electric motor drive, toto has a cylindrical projection 42 located withgether with the advantageous features of hyin the motor seat 22 and has its shaft M prodraulic means for ultimately transmitting power. jecting through an opening formed in the base It is a further object of the present inven- 26 intermediate the motor seat 22 and the pump tion to provide a power unit for moving 2:. verecess 24. The motor is clamped to the base by hicle component including means effective to suitable clamping screws 46. I Y lock the component in adjusted position. The hydraulic power device comprises a cylin- More specifically, it is an object of the present der 5!) having a head 52 at its outer end proinvention to provide a power unit including a vided with an opening 54 through which extends piston and cylinder in conjunction with a fluid a piston rod 56. The piston rod is connected at circuit for establishing a block to lock the pis its inner end to a piston 58. The base 20 inton against movement in one direction in com cludes an annular recess -60 surrounding the seat bination with a friction locking device for lock 26 which receives an out-turned flange provided ing the piston against movement the other on the inner end of the cylinder and which is direction. retained in place by a clamping ring =62 held in Other objects and features of the invention will place by suitable clamping screws 64. The become apparent as the description proceeds, es mounting projection 23 is provided with an openpecially when taken in conjunction with the acing :66 of circular cross-section, the axis of which companying drawings, wherein: is perpendicular to and intersects the axis of Figure 1 is a fragmentary perspective phanthe cylinder 50. m V f a e c Showing the manner in Located within the base 2!] and intersecting which the power unit is attached for effecting the inner end of the pump recess 24 are valve adjustment of the front seat. ports 1i! and i2. The motor and the pump Figure 2 is a plan view of the power unit shown 40 are both reversible so that the ports 10 and E2 in Figure l with the parts in section. may be the inlet or outlet ports depending upon Figure 3 is an end view of the power unit loolzthe direction of rotation of the motor. A drilled ing to the right in Figure 2. passage i l extends longitudinally of the base 20 Figure 4 is a d Vi O the power t 100k and is closed at its outer end by a threaded plug t0 the left in Figure 46 16 or the like. interconnecting the drilled pas Fi ur 5 is an enlarged section on the line sage M with :the interior of the cylinder to is a ure 3. short transverse passage 18. A second drilled Figure 6 is an end view of the locking ring e-m passage 80 extends longitudinally of the base 26 ployed in the cylinder. and connects the port 712 to an external fitting Figure 7 is a section on the line 1-4, Figure 6. 82 located at one end of the base. A metal coh- Figure 8 is a diagrammatic View of the power duit 84 connects the fitting 82 to a second fitunit and hydraulic system. ting 8t located at the outer end of the cylinder Referring now to the drawings, the power unit 58. The passages M and '80 thus connect or is illustrated as pivotally secured to a bracket posite sides of the rotary pump to opposite ends 10 located on the floor of the vehicle beneath 5 of the cylinder 50.

Due to the presence of the piston rod 56 in the outer portion only of the cylinder, movement of the piston requires a larger volume of liquid to flow through passage I8 at the right hand end of the cylinder than through conduit 84 connected to the left hand end of the cylinder as seen in Figure 2. Means must be provided for taking care of this differential flow of fluid. This means takes the form of a fluid reservoir 90 which is formed as an enlarged cavity in the casting located generally between the motor support and the cylinder support. The reservoir 90 is provided with a removable cover plate 92 which in turn is provided with removable filling plugs 84.

As best seen in Figure 5, the passages I4 and 80 are interconnected by a'transversely drilled passage 96 which at its outer ends is enlarged to provide valve chambers 58 and I00. The intersection between the transverse passage 98 and the valve chambers is shaped to form valve seats I02 and I04. Intermediate its ends the passage 96 connects to a short passage I06 providing communication between the interior of the reservoir 90 and the

passages

14 and 80.

Located within the valve chambers 98 and I are ball valves I08 and H0 respectively. The outer ends of the chambers 98 and I00 are closed by removable plugs II2 and H4 respectively, each of which is provided with an inwardly extending portion H8 constituting an abutment limiting movementof the adjacent ball valve away from its seat. Abutment i IS on plug 4 permits valve IIO to move away from its seat substantially further than does valve I88. It will be observed that the dimensions of the enlarged valve chambers 98 and I80 are such that the ball valve I08 or H0 will not prevent flow of fluid longitudinally of the passages 80 or I4 whether the valves are seated or not. Intermediate the ball valves I08 and H6 is a relatively light compression spring II8. Normally, the spring retains both valves away from their associated valve seats, but the efiectiveness of the spring is carefully selected such that the valves may be seated by the accumulation of pressure within the system as will now be described.

Assuming that the motor is operating in a direction to supply fluid through the port 70, passage I4, and passage l8 to the end of the cylinder adjacent the base 28, closing valve IIIl, since full pump pressure acts on the valve. This results in movement of the piston 58 to the left as seen in Figure 2. The entire hydraulic system is at all times filled with fluid so that as the piston 58 moves to the left, fluid is expelled through the fitting 86, conduit 84, fitting 82, and passage 80, to the port I2 of the pump which at this time operates as the inlet port. However, since less fluid is expelled from the cylinder at this time than is required to move the piston 58, an excess of fluid must be made available to the pump. This is provided by the reservoir 90. The passage 88 will at this time be under suction and accordingly, the valve I08 will be retained off its seat and fluid will flow from the reservoir into the passage 80 and thence to the pump.

During the reverse operation of the motor an excess of fluid is expelled from the cylinder through the passages 18 and 14, over what is delivered by the' pump through the passage 80. This excess fluid is accommodated by the reservoir 90. At this time, since the passage 80 1s under the pressure the valve I 08 will be closed thus preventing fluid from flowing directly from the pump to the reservoir. Valve III), being widely spaced from its seat, remains open under the reduced premure in passage I4, letting fluid flow into reservoir 90 from passage 14. Thus, as the excess fluid appears in the system, displaced from the cylinder as previously described, the fluid flows past the valve III! into the reservoir.

In order that the seat will be retained in adjusted position when the motor is de-energized, the following arrangement is efiective: Assuming that the piston 58 is in an intermediate position it will beapparent that mechanical forces applied to the piston tending to move it to the right will expel more fluid from the right of the piston 58 than is drawn into the cylinder to the left of the piston. This excess flow of fluid builds up pressure in the passages I8 and 14, closing valve H8. If fluid is blocked from circulating through the pump, the complete hydraulic circuit is blocked and movement of the piston 58 to the right is effectively prevented. If as sometimes is preferred, the pump is constructed and arranged to provide for a restricted by-pass flow therethrough when it is idle, fluid will pass through the pump from the passage I4 to the passage and will tend to flow through fitting 82, conduit 84, fitting 8B, and thus into the left hand end of the cylinder as seen in Figure 2. However, since more fluid is displaced from the inner end of the cylinder than can flow into the outer end thereof, pressure instantly builds up in passage 80 with the result that ball valve I08 is also forced against its seat. This completely blocks the system and prevents movement of the piston to the right as seen in Figure 2, under application of external mechanical forces.

The system may be considered as a closed hydraulic circuit, diagrammatically shownv in Figure 8. The closed circuit comprises the pump, passages M and 18, the cylinder 50, conduit 84, and passage 80. Due to the differential volume flow into and out of the cylinder, this closed circuit requires replenishment when the piston moves up as seen in Figure 8, and this replenishment is accomplished by flow of fluid from the reservoir 98 past valve I08, which opens freely to permit this flow. On the other hand, movement of the piston down as seen in Figure 8, requires displacement of fluid from the system into the reservoir 90. When the pump is operating in the proper direction, fluid in passage 80 is under pump pressure, and holds valve I08 on its seat. This compresses spring H8 and biases valve IiIl away from its seat, and due to the relatively great clearance between valve I I0 and its seat, valve I I0 remains open to permit flow of fluid past valve II!) to the reservoir. However, when the pump is not operating, valve 108 is not pressed against its seat and hence spring I I8 is not compressed to urge valve IIIl away from its seat. Hence valve III) will close when even slight pressure develops in passage I4, as will occur if external force is applied to move the piston down as seen in Figure 8. If the pump blocks fluid flow when it is not operating, closure of valve II 0 completes a fluid block which prevents movement of the piston to the right. If however fluid can by-pass the pump and flow into passage 80, pressure builds up in the passage, since less fluid can flow into the upper end of the cylinder than is displaced from its lower end as seen in Figure 8. This closes valve I 08 and fluid is thus prevented from being displaced from the closed system. This results in a fluid lock which prevents movement of the piston downwardly as seen in Figure8.

However, the hydraulic block previously described is not eifective to prevent upward movement of the piston 58 as seen in Figure 8, since such movement tends to draw excess fluid into the closed hydraulic system, which flow of fiuid is permitted by movement of the ball valve H0. Accordingly, in order to prevent movement of the piston 58 upwardly as seen in Figure 8, other means are provided.

This means takes the form of an expansible friction locking ring I20 which is shown in detail in Figures 6 and '7. The ring I20 is provided with a radial slot I22 therein which is filled with rubber I24 adapted to form a seal while at the same time permitting expansion and contraction of the ring I20. Preferably, the ring is provided with a peripheral groove I20 adapted to receive a sealing ring I28. The ring I20 is provided with a circular opening I30 including a conical portion I32. As best illustrated in Figure 2', the piston rod 50 extends completely through the piston 58 and has threaded to its projecting end a camming nut I34 which includes a conical camming portion associated with the conical portion I32 of the ring. In addition, the nut I34 includes a circular groove in which is received a sealing ring I36 which cooperates with cylindrical portion I3! of ring H20.

From the construction just described, it will be apparent that the space between the piston 58 and the ring I20 is effectively sealed against the admission of fluid under pressure from the hydraulic system.

The ring I20 is selected such that it normally is in light frictional contact with the interior wall of the cylinder, preferably, this contact being effected through the sealing ring I28. The dimensions of the conical camming portion on the nut I34 and the conical portion I 32 of the ring are such that the ring is permitted slight axial movement relative to the piston 58.

When mechanical forces are applied to the piston rod tending to move the piston to the left, as seen in Figure 2, initial movement of the piston is not transmitted directly to the expansible friction locking ring I20. This ring will drag behind and as it does so it rides upon the camming surface of the nut I34, thus expanding the ring into tight locking frictional contact with the interior of the cylinder wall. Obviously, the cone angle of the camming parts will be selected such as to provide the requisite camming action and will depend upon the frictional drag of the expansible ring on the inner surface of the cylinder.

As will be apparent from the foregoing, the construction thus prevents any substantial movement of the piston in the cylinder in either direction by the application of external mechanical forces. When the friction locking ring I20 has been brought into tight frictional contact as previously described, it will be apparent that this frictional lock is released upon the application of fluid pressure into either side of the piston to effect further adjustment of the seat. Thus, when pressure is admitted to the left of the piston, as seen in Figure 2, the piston moves to the right and its initial movement moves the camming nut I34 out of camming relation to is applied to the right of the piston after the 6, piston "assembly. has been 'frictionally" locked, initial pressure of the fiuidwill act against the clamping ring. Since the admission of fluid to the space between the clamping ring and the piston is eifectively prevented by the sealing means described, this will result in movement of the clamping ring toward the piston 50, thus releasing the frictional clamp.v

While in the foregoing system reliance is placed on a hydraulic block to prevent move ment of the piston in one direction;v it will be apparent that if preferred, the frictional locking ring I20 could be duplicated and provided at opposite sides of the piston so that movement of the piston upon the application of external mechanical forces would be prevented in both directions by frictional interlock rather than by a hydraulic lock.

The drawings and the foregoing specification constitute a "description of the improved hydraulic power unit in such full, clear, concise and exact terms as to enable any person skilled in the art to practicethe invention, the scope of which is indicated by the appended claims.

What I claim as my invention is:

1. In a power unit, a cylinder, a piston assembly in said cylinder comprising a piston rod, a piston rigidly connected to said piston rod, an expansible friction ring having a central opening therethrough, said piston having a frustoconical cam extending axially therefrom with its smaller end disposed toward said piston, the larger end of said cam extending through the central opening in said friction ring, said ring being relatively movable away from and toward said piston respectively to effect positive expansion and to permit contraction of said ring, said piston having peripheral sealing means engaging the cylinder wall, said ring having peripheral sealing means engaging the cylinder wall and in relatively light frictional contact therewith when said ring is contracted, and annular sealing means intermediate said cam and the central opening in said ring.

2. Structure as defined in claim 1 in which said ring is provided with a generally radial slot extending between its central opening and its periphery, and means effective to seal said slot in all stages of expansion of said ring.

3. Structure as defined in claim 2 in which the said means comprises a rubber-like material located in said slot and bonded to the confronting edges of the slot.

4. A friction-lock piston and cylinder device comprising a cylinder, a piston movable in said cylinder annular sealing means carried by the periphery of said piston effective to provide a seal between the piston and cylinder, a cam extending axially from said piston and rigidly secured thereto, said cam having a camming portion of increasing cross-section in a direction away from said piston, an expansible friction ring having a central opening through which said cam extends, the central opening having a cam surface cooperable with the camming portion of said cam and effective to expand said ring radially upon relative axial separation between said piston and ring, annular sealing means carried by the periphery of said ring eifective to provide a seal between the ring and cylinder and to provide a light frictional drag on the cylinder inner wall when said ring is in contracted condition, and annular sealing means interposed between said cam and the central opening in said ring to maintain a seal during relative axial movement between References Cited in the file of this patent Said Piston and ring- UNITED STATES PATENTS 5. Structure as defined in claim 4 in which said friction ring has, a general radial slot exf Name Date tending from the central opening thereof to its 5 g' Galmway June 1940 periphery, and sealing means efiective to seal said clench June 1940 slot in all stages of expansion of said ring. 5*775 Horton 3, 1943 6. Structure as defined in claim 5 in which et a1 g i2 sai sealin means com rises arubber-like mate- 1 e d g p 2,432,895 Horton Dec. 16, 194':

rial in said slot and bonded to the confronting 10 edges of said Slot 2,479,063 Forsythe Aug. 16, 1949 STEWART MCLEOD 6,68 McLeOd Feb- 19, 1952